The invention relates to a fuse element including a hollow body, which is constituted by a tubular wall surrounding an internal space and has two opposed open end faces, a fusible conductive element, which extends in the internal space between the two end faces of the hollow body, and two contact caps with a respective base and adjoining side walls, the bases of two contact caps at least partially closing the internal space at the end faces and the side walls overlapping a respective section of the outer surface of the wall of the hollow body, whereby two end sections of a conductor of the fusible conductive element extend out of the internal space through the end faces around the wall of the hollow body so that they are arranged between a respective side wall of one of the contact caps and a section of the outer surface of the hollow body. The invention further relates to a method of manufacturing a fuse element.
A fuse element of the type referred to above has been known for a long time from the prior art. In a known element, the hollow body is for instance, a small glass tube with an internal space of circular cross-section. Extending within the internal space is a fusible wire, the ends of the wire being bent around the ends of the small tube beyond the end faces. Pushed onto the ends of the tube are metallic contact caps such that they are retained in position on the ends of the tube in a force-locking manner and thus clamp the fusible wire between the outer wall of the tube and the inner wall of the caps. The ends of the fusible wire can also be soldered into the caps. These fuses, which have long been known, have, for instance a length of ca. 20 mm, whereby the metal caps positioned on both sides can have an external diameter of ca. 5 mm and a length of ca. 6 mm. Such fuses are commonly inserted or screwed into correspondingly shaped casings.
Starting from this very old prior art, which is widely used in electronic devices, e.g. radio and television receivers, a series of further fuse elements were developed for more recent and more special applications. Fuse elements with considerably reduced dimensions, amongst other things, were developed for applications in which only a small installation space is available. For instance, there are fuses in which a fusible conductor extends within the cylindrical internal space of a small ceramic tube of less than 10 mm length.
If a fusible conductor is subjected for a predetermined minimum period of time to a sufficiently large current, it melts. The current flow is thus supposed to be interrupted. However, when the fusible conductor melts, depending on the applied voltage and the current driving ability of the circuit, in which the fuse is inserted, an arc can form between the end contacts, that is to say between the contact caps of the fuse element, which enables the continued flow of power. Manufacturers of fuse elements are anxious to suppress the formation of such an arc or to limit the time of current flow rendered possible by the arc. Particularly when an alternating voltage is applied to the fuse element, the formation of a new arc in the event of a melted fusible conductor, and after the voltage has passed one or more times through zero, is to be avoided or reduced.
Therefore, the object of the invention is to provide a fuse element of the type referred to above which exhibits a minimal tendency to maintain an arc after melting of the fusible conductor, even if it is of relatively small size.